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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 | /* * Copyright 2013, Michael Ellerman, IBM Corporation. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #define pr_fmt(fmt) "powernv-rng: " fmt #include <linux/kernel.h> #include <linux/of.h> #include <linux/of_address.h> #include <linux/of_platform.h> #include <linux/slab.h> #include <linux/smp.h> #include <asm/archrandom.h> #include <asm/io.h> #include <asm/prom.h> #include <asm/machdep.h> #include <asm/smp.h> struct powernv_rng { void __iomem *regs; unsigned long mask; }; static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng); static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val) { unsigned long parity; /* Calculate the parity of the value */ asm ("popcntd %0,%1" : "=r" (parity) : "r" (val)); /* xor our value with the previous mask */ val ^= rng->mask; /* update the mask based on the parity of this value */ rng->mask = (rng->mask << 1) | (parity & 1); return val; } int powernv_get_random_long(unsigned long *v) { struct powernv_rng *rng; rng = get_cpu_var(powernv_rng); *v = rng_whiten(rng, in_be64(rng->regs)); put_cpu_var(rng); return 1; } EXPORT_SYMBOL_GPL(powernv_get_random_long); static __init void rng_init_per_cpu(struct powernv_rng *rng, struct device_node *dn) { int chip_id, cpu; chip_id = of_get_ibm_chip_id(dn); if (chip_id == -1) pr_warn("No ibm,chip-id found for %s.\n", dn->full_name); for_each_possible_cpu(cpu) { if (per_cpu(powernv_rng, cpu) == NULL || cpu_to_chip_id(cpu) == chip_id) { per_cpu(powernv_rng, cpu) = rng; } } } static __init int rng_create(struct device_node *dn) { struct powernv_rng *rng; unsigned long val; rng = kzalloc(sizeof(*rng), GFP_KERNEL); if (!rng) return -ENOMEM; rng->regs = of_iomap(dn, 0); if (!rng->regs) { kfree(rng); return -ENXIO; } val = in_be64(rng->regs); rng->mask = val; rng_init_per_cpu(rng, dn); pr_info_once("Registering arch random hook.\n"); ppc_md.get_random_long = powernv_get_random_long; return 0; } static __init int rng_init(void) { struct device_node *dn; int rc; for_each_compatible_node(dn, NULL, "ibm,power-rng") { rc = rng_create(dn); if (rc) { pr_err("Failed creating rng for %s (%d).\n", dn->full_name, rc); continue; } /* Create devices for hwrng driver */ of_platform_device_create(dn, NULL, NULL); } return 0; } subsys_initcall(rng_init); |